Separate psu for microcomtroller

[emosms]

Hi, in a project with digital audio curcuits (dac, spdif transmitter, etc) and microcontroller, is it a good idea:
1. to have a seporate regulator for the microcontroller part
2. to have galvanically isolated psu (seporate transformer/secondary winding).
3. to have a seporate dgnd for the microcontroller and connection between
Both the dgnd onto the psu block?

The microcontroller part would power several relays, arduino, several i2c devices.
The signal digital part would power, f.example dac, spdif transmitter, bluetooth receiver, e.t.c.

Is it enough to have one 5v /3.3v psu and use local regulators with low synamic impedance at chosen points of load (the closest the possible on the pcb)

What about seporate dgnd for the microcontroller and microcontroller devices, to prevent noises going into the audio signal part?

Regards

 

[emosms]

Or mby just seporate path and supply fo the relays?
Anyway. The arduino will be a seporate pcb as well..

I am starting my projects as usual:
- dimensions estimation
- back and front panel in regards with the functionality
- diy the project box
..
- now it is time to take some important decisions on the psu block..

The whole stuff is going to be modular architecture, central psu block.